Surfacing glass sheets or plates



G. E. RICKNER ETAL SURFACING GLASS SHEETS OR PLATES May 20, 1952 2,597,182

Filed March 31, 1949 INVENTORS ra/7e @bffwc md ATT ORNE YS Patented May 20,A 1952 UNITED STATES FICE SHEETS OR .PLATES Oscar F. Koenig. Ottawa,

Application March 31,

14 Claims. 1

The present invention relates broadly to the facing of glass blanks fcan Y:be accomplished by smoothing or preliminarily polishing the blanks, after grinding and before polishing, .withafmixture of rouge Vand pumce rubbed 'over 'th'ejiglass blanks by relatively soft, resilient .runners or ools.

While not restricted to such use, thewpresent invention has proved to be of outstanding value when employed in the socalle'dfcontinuousimethod of grinding and polishing plate fgla'ssblanks. In this method, as now quite widely'fpraoticed, a plurality of rough glass blanks'aremuntedupon a series of cars or tables,.arrangedfin--end-to-end relation and movable continuously 'allongeJ fdenite predetermined pa'thtol carry thelglas'silarlks rst through a grinding and ,then through a polishing area. In thegrindingaif'ea.theblanks are subjected vto the Aabrasive,actonvof jsadof progressively ldecreasing coarseness, under. heavy iron runners, and in .theu.polishing. ..farealthe ground surfaces of theblanksl are Lpdlishdwith rouge under felt pads.

This is the method th used by the companyto lw'hic'lfthis application has been assigned formanyyears. NOW, however, we have kdiscovered"thatbetter results can b'ehad, that the surfacing operationcanbe rbetter-controlled, and .that higher production-speed can be attained, -by subjectinglthel.glasstoQthespecial smoothing operationofth'is invention:,-vvhileri-t is passing 4between Athe grindingand `polishing areas. y n

In fact, where this 4invention .,has :been incorporated in a grindingand.polishing-line, .wehaveincreased the speedfof the line,finf.actualicom mercial production `from l-110 to t140 .inchestper `minute with remarkably. good 4results ...inzsurace nish of Athe glass ;Y andthis-i-ncreasen line 'speed represents Van increased production lof' between 25 and 30% lon-thisline. Y

We 'do :not claim to -beithe :first l:to :suggest .--the broad idea of :smoothing -or prliminarily-zpolish- 'ing glass blanks between-:the-conventionalfgrinding and polishing steps, because this hasbeen suggested before. And variousftypes :ofabrasives 'such :as `-extremely fine `:or #wasteA fsand, vgalvr'iet, nezpumicacetc., applied-:withftoolsofi arent .types', have-also:beensuggestedaforlthegpurpose.

at has beenvgenerally .L

1949, a"Serialllo. l841,674

.-2 "But none of lthese procedures that We haveftried Lhave LWorked to .Your satisfaction, and with Anone of them have we been Sable to accomplish Athe @results which we have-attained .with our-.present f5 smoothing technique.

4lt is 1"therefore an faim. of this 'invention to :i-proyvide a Dcc )rrmaercially successful rsmoothing techniquefwhich, -when employed between :conventional grinding and polishing steps, will :not 'only Alli) improve surface Vfqualityfo'f the glass, :but will also permit itto-'be surfaced in ra yshorter'length f'f Ltime i and/or, in the f case. of a continuous .prockfess, vvvith fewer ltool's.

f n'other -o'bjcct Lis the :provision 'of a smoothing yrouge andfpumiceisfemployedas the abrasive.

.Anotherxobjectis to :provide a method -of the above ycharacter in which 'a special mixture -of 'Ireugavpumice'and copperas in water is rubbed 201e-ver thegroundfglass s'urfaces by relativelysoft,

Other objects and advantages of the-invention Fig.4 isafbo'ttomview of thetoolshow'n in l Referring :now more .particularly to "the drawings, there has been illustratedjin f1 a jwell Tknovvnftype of. continuous grinding and polishing l Yfline, lindicatedgenerallyb'y thenumeral 1.0. The .-xexitend of-thegrinding area is indicated atthe 50 left-of A.this ffigureat ll,.and the `entrance jend of `the,polish-iri-g areaisindicated at the vright at Y4.2.

Intheline, a. series of tables 'I'3 r`are bolted totgetlaeiulto.form a continuous gl'asissupportingjsur- 5`5 rface on which blanks |4 areb'edde'd'in vag'layer of elliptical in shape, give very good results.

plaster of Paris I5. The tables I3 are continuously moved in the direction of the arrows I6 to carry the blanks rst beneath a series of iron grinding runners I'I, beneath which sand of progressively increasing neness is fed, and then beneath a series of polishing heads I8, which are supplied with rouge in any well known manner.

Suitable cleaning means, shown diagrammatically at I9, are provided at the end of the grinding area to remove all traces of grinding sand from the glass surfaces before they move toward the polishing area.

In practicing our invention, we interpose, in the area 20, between the grinding and polishing areas, a plurality of smoothing runners or tools 2 I. These tools may be made in various sizes and shapes and can be arranged in any one of a number of diierent ways. However, in actual practice, we have found that four sets of three overlapping tools each, and with the tools themselves The individual tools, located as shown in Fig. l, are rotated in the directions of the arrows, and the sets of tools may be reciprocated transversely of the glass on the line if desired.

Satisfactory results have been obtained when the individual smoothing tools are rotated at any speed between 40 and 100 R. P. M., but best results seem to be'had at speeds of around 55 R. P. M.

Practically any construction of smoothing tool can be employed with our invention so long as the glass contacting surface of the tool is compressible, and not too soft. For example, either felt or rubber tools can be used. However, we prefer a l felt tool of the general character shown in Fig. 2,

fact that the fissures or cracks 26 betweenV the adjacent strips assist in distributing the rouge and pumicermixture uniformly over the smoothingface 21 of the tool.

An alternate form of tool that has been used with good results is shown in Figs. 3 and 4, and comprises a plate 28 carried at the end of a spindle 29 and having a thick sheet or pad of felt or similar compressible material 3] covering, and preferably cemented to, its 1ower face 3i. The lower, or glass contacting face of the felt pad 30 is preferably provided with grooves 32, leading from a central opening 33 to the edges of the tool, to distribute the rouge and pumice mixture over the smoothing face of the tool. And this may be further facilitated by bays 34 also leading out from the central opening. In the case of either of the tools shown in Figs. 2 and 3, the mixture of rouge and pumice may be supplied to the tool through a passageway 35 in the spindles 23 and 29 orit may be deposited on the glass in the path of travel of the tool.

A pointed out above, we have found that an extremely eicient smoothing action, which influences and improves the entire surfacing operation to a remarkable degree, can be obtained by treating the glass, between the grinding vand polishing areas, with a mixture of kpumice and rouge rubbed over the ground glass surfaces with compressible tools of the general character -just described.

Surprisingly enough, we have also discovered that a coarser grade of pumice than has heretofore been considered to be adapted to nishing glass surfaces gives the best results in the rouge and pumice mixture. Specifically, grades between .0% and ill/g special should be used for proper smoothing, because grades above .0% are found to be too coarse, while grades below .01/2 special are too ne.

The term 6% is used by pumice manufacturers to indicate a grade of pumice consisting of substantially the particle sizes, in substantially the proportions, shown in the column at the left of the table below; and .01/2 special is used to indicate a grade of pumice consisting of substantially the particle sizes, in substantially the proportions, shown in the extreme right column in the table:

Per Cent Between Sieves Grade of Pumice l O V X Y o k 4 Special FP FI FP 2. 7 'l 0. 1 .l 9.6 0. 4 l. l .O 17. 4 9; 8 15.3 .7 26.1 30.0 39.8 .8 27. 5 35. 0 23.3 2. 9 8. 2 11.1 5.3 +325 5. 5 5. 5 7. 5 14. 7 325 4. 0 3. 0 6.2 0. 4

Total 100. 0 100.0 100. 0 100. 0

N=None.

P=Pieces (number indicated). VFP= to 100 pieces. 1 f FP=100 to 200 pieces. T=About 300 pieces. Recorded to nearest .1%.

Grades X and Y in the table are grades of pumice, falling between 6% and .0 1/2 special, that were made up especially for this purpose. Any of .these four grades of pumice, or any other grade use in regular commercial production.

After selecting the proper grade of pumice, the pumice is mixed with rouge, preferably in the ratio of 165 pounds of pumice to 50 pounds of rougein 600 gallons of water or other suitable liquid, whichhas previously been made up with an amount of copperas, or ferrous sulphate (FeSOi), to form lacid and to give a reading of 0.6 on the Baume scale for heavy liquids.v

, Some variations inthe proportions of the ingredients in the rouge and pumice mixture are permissible while still maintaining its'eifectiveness. However, we have found that a range between and 165 pounds of pumice to 50 pounds of rouge is best for most effective smoothing. Within this ran-ge the amount of work done will increase by approximately 1 micro inch for each additional 20 poundsrof pumice in the mixture. On the other hand, a mixture containing much more than pounds of pumice to 50 pounds of rouge does not iiow as satisfactorily, and a mixture containing less than V100 pounds of pumice, to 50 pounds of rouge, will accomplish only slightly more work than will rouge or pumice alone.

Similarly, we prefer to use approximately 50 pounds of rouge to 165v pounds of pumice in the mixturaalthough anywhere in the range of 40 to 60 pounds of rouge'to 165 pounds of pumice gives assurez good results. Even a slightly wider range can be used, but we seem to lose the amount of work the lpumice can do in Vthe mixture when the amount of. rouge .is .increased much above 60 pounds-and amounts of rouge. outside of a range of to 7.5 pounds to'165 pounds of pumice will not Igive results thatA are commercially satisfactoryfor our purpose, although some good effects will be noted all the way down the scale.

In other words, While there are denite proportions of rouge and pumice that should be adhered to in order to obtain the greatly improved results we have noted from our novel smoothing technique, a mixture of rouge and pumice in any proportion will give better results than either rouge or pumice alone. Thus, the use of rouge alone in the smoothing area will give no different results than are obtained in the polishing area l2, and pumice when used without rouge is a thin watery mix which runs away and will not adhere eectively to the smoothing tools.

As indicated above, we use about 600 gallons of water for the rouge and pumice mixture, but this can be varied to meet actual working conditions, the important thing being to keep a concentration, that is not too great to clog the pipes, nor so dilute as to wash out the smoothing material from the tools before it can do the required work.

The water should contain copperas (ferrous sulphate) and we prefer an amount to give a reading for the water and copperas mixture of 0.6 on the Baum scale for heavy liquids. The presence of the copperas is important in the mixture because it acts to hold the rouge in suspension in the water and to disperse the rouge particles, causing them to float through the liquid without sticking together.

Moreover, the rouge and copperas in the mixture combine to provide a proper carrying liquid of the specific gravity necessary to suspend the pumice particles, and provides a bonding agent tending to effectively hold the pumice in working engagement with the smoothing tools.

Although we prefer an amount of copperas to give a reading of 0.6 on the Baum scale, an amount that will give a reading within the range of 0.4" to 1.0 Baume can be used. Below the minimum, however, the rouge will not be properly suspended in and dispersed vthrough the liquid, while an amount of cop-peras above the maximum will cause the block to harden to a point where it will run over the glass with too little smoothing effect.

In this connection, and particularly when felt tools are used, it is extremely important to control the amount of copperas used, and to clean the felts frequently in order to maintain them in a sufficiently soft condition to give proper smoothing.

It is also desirable to provide a cleaning means at the end of the smoothing area 20, that is similar to the cleaning means l9,to remove the smoothing materials from the surface of the glass before it passes into the polishing area I2.

In fact, it is to be'understood that the forms of the invention herewith shown and described Yare to be taken as illustrative embodiments only of the same, and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the `subjoined claims. Y

We claim: 1

1. In a method of :surfacing glass sheetsor plates in which asurfaceof such a platefis first ground with sand` of progressivelyl increasing fineness .applied with hard tools and then polished with rouge'under relatively soft tools, they step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and-pumice with copperas in a liquid carrier over .said surface with compressible tools.

- 2. Ina method of surfacing glass sheets or plates in' which a surface of such a plate is rst ground with sand of progressively increasing neness applied. with hard tools and then polished with rouge under` relatively soft tools, the' step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumicein proportions of between 25 and 82.5 parts vof rouge by weight to 165 parts of pumice by weight with copperas in a liquid carrier over saidvsurface with compressible tools. -3. In a method Vof surfacing glass sheets or plates in which a surface of such a plate is first grounded with sand .of progressively increasing neness applied with hard tools and rthen polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in proportions of between 25 and 82.5 parts of rouge by weight to 165 parts of pumice of a grade between .0% and .01/2 special by weight with copperas in a liquid carrier over said surface with compressible tools.

4. In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is first ground with sand of progressively increasing fineness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in proportions of between 25 and 82.5 parts of rouge by weight to 165 parts of pumice of a grade between .0% and .01/2 special by weight in water to which copperas has been added to give a reading of between 0.4 to 1.0 on the Baum scale over said surface with compressible tools.

5.In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is first ground with sand of progressively increasing neness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture ofrouge and pumice in proportions of between Li0 and 60 parts of rouge by weight to 165 parts of pumice of a grade between ".0% and .01/2 special by weight in water to which copperas has been added to give a reading of between 0.4 and 1.0 on the Baum scale over said 1 surface with compressible tools.

6. In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is rst ground with sand of progressively increasing neness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in proportions of 50 parts of rouge lby weight to between and 165 parts cf pumice of a grade between ".0% and .01/2 special by weight in water to which c010- peras has been added to give a reading of between 0.4 and 1.0 on the Baume scale over said surface with compressible tools..

v7. In a method of surfacing glass sheets o r plates or the like in which a surface of suchl a plate is rst ground with sand Qfprogressively increasing neness applied with hard? tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mix-v ture of rouge andpumice in. Vproportions of be; tweenA 40 and 66 parts of rouge by weight to 165 parts of pumice of a grade between .0% and .01/2 special by Weight inwater to which copperas has been added to give a readingV of between 0.4 and 1.0 on the Baume scale over said surface with compressible tools.

8. In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is iir'st ground with sand of progressively increasing nneness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding andl before polishing by rubbing mix-f ture of rouge and pumice in proportions of between Lil) and 66 parts of rouge by Weight to 165 parts of pumice of a grade having substantially the following per cent of particles of the indicated fneness between sieves:

by Aweight in water to which copperas has been added to give a reading of between 0.4" and 1.0 on the Baume scale over said surfaces with compressible tools.

9. In a method of surfacing glass sheets or plates or the like inV which a surface of such a plate is rst ground with sand of progressively increasing iineness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in proportions of between 40 and 66' parts of' rouge by weight to 165 parts of pumice of a grade having substantially the following per cent of particles of the indicated neness between sieves:

. Per Cent Be- 7 T Sle e B' tween Sieves 42 N 48 121)-,- 60' F P 65 2. 7. 80 9. 6 100 17. 4 150 26. 1 200 27. 250 8. 2 +325 5; 5 325 3. 0

by weight in water to which" copperas has been added to give a reading of between 0.4 and 1.0 on the Baume scalev over saidsurfaceswith com- Vpressible tools.

Per Cent Be# Sieve No tween Sieves 42 N 4S 5P 6o FB 65 T 80 0. 4 100 9. 8` 150 30. 0 200 35. 0 250 1I. 1 +325 ''.l 5 -325 6. 2

by weight in water to which cpperas has been added to give a reading of between 0.4 and 1.0 on the Baume scale over said surfaces with com'- pressible tools. y

1l. In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is first ground with sand of progressively increasing flneness applied with hard tools' and then polished with rouge under relatively soft tools, the step of soothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in a liquid carrier over said surface with compressible tools in proportions of substantially parts of rouge by weight to 165 parts of pumice of a grade having substantially the following percent of particles of the indicated neness between sieves:

Per C ent Be- Se No' tween Sieves 42 48 12R-I- FP 7 9. 6` 17. 4 26;'1 20()` 27. 5 250 8. 2 +325 5. 5 325 3. 0

face with compressible tools in proportions ofy substantially 50 parts of rouge by weight to 165 partsof pumice of a grade having substantially the following percent of particles of the indicated iineness between sieves.

Per Cent Be Sieve No' tween Sieves 42 4s N so 4P c5 VFP so o. 1 o 14. o o 42. 7 o 3o. s 50 25 -325 4. o

by weight in water to which copperas has been added to give a reading of substantially 0.6 on the Baum scale over said surface with compressible tools.

13. In a method of surfacing glass sheets or plates or the like in which a surface of such a plate is rst ground with sand of progressively increasing flneness applied with hard tools and then polished with rouge under relatively soft tools, the step of smoothing said surface after grinding and before polishing by rubbing a mixture of rouge and pumice in a liquid carrier over said surface with compressible tools in proportions of substantially 50 parts rouge by weight to 165 parts of pumice between grades characterized by having substantially the following per cents of particles of the indicated flneness between sieves:

Per Cents Between Sieve No. Sieves 60 4P FP 65 VFP 2. 7 80 0. 1 9. 6 100 14.0 17. 4 150 42. 7 26. 1 200 30. 8 27. 5 250 2. 9 8. 2 H325 5. 5 5. 5 -325 4. 0 3. 0

by weight in water to which copperas has been added to give a. reading of substantially 0.6" on 10 the Baum scale over said surface with compressible tools.

14. In a method of surfacing glass sheets or plates or the like, the step of smoothing a surface of such a plate by rubbing a mixture of rouge and pumice in proportions of between 40 and 66 parts of rouge by weight to 165 parts .of pumice between grades characterized by having substantially the following per cents of particles of the indicated neness between sieves:

. Per Cents Between Sieve No. Sieves 42 48 N 12P:|: 4P FP VFP 2. 7 0. 1 9. 6 14. 0 17. 4 42. 7 26. l 200 30. 8 27. 5 250 2. 9 8. 2 +325 5. 5 5. 5 -325 4. 0 3. 0

by weight in water to which copperas has :been added to give a reading between 0.4 and 1.0 on the Baume scale over said surface With compressble tools.

GEORGE E. RICKNER. OSCAR F. KOENIG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 538,803 Wefers May 7, 1895 1,231,307 Spellman June 26, 1917 1,373,532 Showers Apr. 5, 1921 1,996,369 Ely Apr. 2, 1935 2,000,240 Long May 7, 1935 2,023,275 Long Dec. 3, 1935 2,309,819 Benner Feb. 2, 1943 FOREIGN PATENTS Number Country Date 511,098 France Sept. 18, 1920 

